Table 4.
Studies on oral contraception and venous thromboembolism. Risk estimates are in current users of oral contraceptives compared with non-users or never users unless stated otherwise
| Study | Period of data sampling | No with venous thromboembolism | Rate ratio (95% CI) for combined oral contraceptives | ||
|---|---|---|---|---|---|
| Pill with levonorgestrel | Pill with desogestrel or gestodene | Pill with drospirenone | |||
| Blomenkamp1 | 1988-92 | 126 | 3.8 (1.7 to 8.4) | 8.7 (3.9 to 19.3) | — |
| WHO3 | 1989-93 | 433 | 3.6 (1.4 to 7.9) | 7.4 (4.2 to 12.9) | — |
| Jick2 | 1991-4 | 80 | Reference | 1.8 (1.0 to 3.2) | — |
| Spitzer4 | 1991-5 | 471 | 3.2 (2.3 to 4.3) | 4.8 (3.4 to 6.7) | — |
| Lewis7 | 1993-5 | 502 | 2.9 (1.9 to 4.2) | 2.3 (1.5 to 3.5) | — |
| Farmer5 | 1991-5 | 85 | 3.1* (2.1 to 4.5) | 5.0‡ (3.7 to 6.5) | — |
| Todd8 | 1992-7 | 99 | Reference | 1.4 (0.7 to 2.8) | — |
| Bloemenkamp6 | 1994-8 | 185 | 3.7 (1.9 to 7.2) | 7.0 (NA) | — |
| Lidegaard12 | 1994-8 | 987 | 2.9 (2.2 to 3.8) | 4.0 (3.2 to 4.9) | — |
| Dinger13 | 2000-4 | 118 | Reference | 1.3 (0.8 to 2.0)† | 1.0 (0.6 to 1.8) |
| Seeger14 | 2001-4 | 57 | Reference | Reference | 1.0 (0.2 to 18.6) |
| Lidegaard (current study) | 1995 | 4213 | 2.0 (1.8 to 2.3) | 3.6 (3.3 to 3.8) | 4.0 (3.3 to 4.9) |
WHO=World Health Organization; NA=not available.
*Incidence per 10 000 woman years.
†Our calculation based on data in publication.